Catamaran for pastime, model construction or racing in any competition rating, with induced hydrodinamic stability

ABSTRACT

A catamaran for pastime, model construction or racing with induced hydrodynamic stability, having a hull with a board (1) and a pair of longitudinally extended semi-immersible appendages (2, 3; 8, 9; 13, 14; 24, 25) arranged parallel to each other symmetrically to the center-line of the hull, the respective bottoms of which, at the bow tips (4, 5; 12, 12a; 21, 22; 32, 33) of said appendages, have mutually opposite slopes, each slope being contrary to the slope of the respective aft rest of the bottom with respect to the median symmetry plane of the hull.

FIELD OF THE INVENTION

The present invention concerns a catamaran with induced hydrodynamicstability.

BACKGROUND OF THE INVENTION

As it is known, racing catamarans or catamarans used for pleasureboating, usually called "two-points", or also the relevant models, havea forward configuration with two convergent bottoms or hulls, such asthe bottoms of the monohull motorboats. This configuration has majordrawbacks, especially during the races run in basins not perfectly calm.

In fact, it may happen that one of the two bottoms slips into the waveseither due to a piloting mistake or falling down from the jumps thecatamaran may make. In this way, it often occurs that, at best, there isjust a spin-around of the catamaran, which at cruising speed can be verydangerous anyway, whereas, at worst, there may be the complete capsizingof the catamaran with the possible ejection of the pilot, with easilyimaginable consequences.

U. S. Pat. No. 3,113,543 discloses a boat with two catamaran-likeappendages having opposite slopes developing into a V-shaped hull at theboat end with the aim of obviating the difficulties of an invertedV-bottom boat, which is not suitable for high speeds in racing.

However, this solution could not be adopted in a real catamaran toovercome the above-mentioned problems due to the high speed experiencedin racing.

The aim of the present invention is to eliminate or substantially reducethe above-mentioned drawbacks of known type catamarans by devising aninduced hydrodynamic stability catamaran, which eliminates thepossibility of spin-arounds or capsizings of the catamaran itself.

Within the scope of the mentioned aim, an object of the presentinvention is to obtain a catamaran maintaining the same driving andperformance characteristics of known type catamarans.

Not last object of the present invention is to obtain a high reliabilitycatamaran, fairly easy to build and at competitive costs.

SUMMARY OF THE INVENTION

The aim stated above, as well as the mentioned objects and others whichwill be clearer later on are achieved by an induced hydrodynamicstability catamaran including a hull formed by a pair of longitudinallyextended semi-immersible appendages, arranged parallel to each other andsymmetrically to the centre-line of the hull, the respective bottoms ofwhich, at the forward ends of said appendages, have mutually oppositeslopes, contrary to the slope of the aft rest of the bottom, withrespect to the median symmetry plane of the hull.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will be apparentfrom the description of some preferred, but not exclusive, embodimentsof an induced hydrodynamic stability catamaran according to theinvention, illustrated as indicative and non-limiting examples in theannexed drawings, wherein:

FIG. 1 is a perspective view from below of a first embodiment of acatamaran according to the invention;

FIG. 2 is a front elevational view from the stern side of the catamaranof FIG. 1;

FIG. 3 is a plan view from below of the catamaran of FIG. 1;

FIG. 4 is a side elevational view of the catamaran of FIG. 1;

FIG. 5 is a front elevational view from the bow side of the catamaran ofFIG. 1;

FIG. 6 is a perspective view from below of a second embodiment of acatamaran according to the invention;

FIG. 7 is a plan view from below of the catamaran of FIG. 6;

FIG. 8 is a front elevational view from the bow side of the catamaran ofFIG. 6;

FIG. 9 is a perspective view from below of another embodiment of acatamaran according to the invention;

FIG. 10 is a plan view from below of the catamaran of FIG. 9;

FIG. 11 is a perspective view from below of a further embodiment of acatamaran according to the invention;

FIG. 12 is a side elevational view of the catamaran of FIG. 11; and

FIG. 13 is a side sectional elevational view along the axis of thecatamaran of FIG. 11.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the FIGS. from 1 to 5, an induced hydrodynamic stabilitycatamaran includes a hull, schematically represented by a board 1provided with a pair of longitudinally extended semi-immersiblestreamlined appendages 2 and 3 arranged along parallel sides of theboard 1. The bottoms of the bow tips 4 and 5 of the semi-immersibleappendages 2 and 3 have mutually opposite slopes, which are alsocontrary to the slope of the respective aft rest of the bottom.

Each appendage 2 and 3 has at least one step, respectively identified bythe reference numerals 6 and 7, which defines said bow tips 4 and 5 atthe bottom slope variation, going from the stern to the bow of the hull.In a first embodiment, steps 6 and 7 form an inverted "V", going fromstern to bow, as better illustrated in FIGS. 1 and 3.

In addition, at the inner edge of each appendage 2 and 3 there may beprovided a runner 41 acting as a deflector to divert water out of thetunnel between the two appendages or boots, as well as preferably abevelled portion 42 at the outer edge, with the purpose of reducing to aminimum the transverse skidding in case of falling down on one bootonly.

Referring to FIGS. from 6 to 8, in a second embodiment, havingappendages 8 and 9, steps 10 and 11 and divergent bow portions 12 and12a, the steps 10 and 11 form a "V", going from stern to bow, as betterillustrated in FIGS. 6 and 7.

Referring to FIGS. from 11 to 13, in another embodiment, havingappendages 13 and 14, steps 15, 16, 17, 18, 19 and 20 and divergent bowportions 21 and 22, the steps 15, 16, 17, 18, 19 and 20 form three"V's", going from stern to bow. At the steps 15, 16, 18 and 19 there arenotches 23 which wedge themselves into both appendages 13 and 14.

Referring to FIGS. 9 and 10, in an alternative embodiment, havingappendages 24 and 25, steps 26, 27, 28, 29, 30 and 31 and divergent bowportions 32 and 33, the steps 26, 27, 28, 29, 30 and 31 form three"V's", going from stern to bow. At the steps 26, 27, 29 and 30 there arenotches 34 which wedge themselves into both appendages 24 and 25, likein the embodiment of FIGS. 11-13.

Differently from said embodiment, in this model between the pairs ofsteps 27/28 and 30/31 there is provided a tier of steps, each formed bythree steps respectively 35, 36 and 37; 38, 39 and 40, which slopesupwards from the bottom edge towards the longitudinal axis thereof.

Advantageously, the catamaran according to the invention, in its variousembodiments, has the appendages bows with divergent slope bottoms, asstated above, which, in case of immersion into a wave, act as a rudder,thus putting the catamaran straight, either in the racing or pleasureboating type, and in the model construction type.

The invention as it has been conceived is susceptible of manymodifications and variations all within the scope of the inventiveconcept. Moreover, all the details may be replaced by other technicallyequivalent elements.

In practice, the materials used as well as the dimensions may be any,according to the requirements.

I claim:
 1. A catamaran for pastime, model construction or racingparticularly suitable to high speeds, having a hull with a board and apair of longitudinally extended semi-immersible appendages arrangedalong parallel sides of the board and symmetrically to a center-line ofthe hull, each of said appendages having a bow tip, a stern, an inneredge, and a bottom; anda runner on the inner edge of each appendage,said runner acting as a deflector; wherein the respective bottoms atboth bow tips of said appendages have mutually opposite slopes and therespective bottoms at both sterns of said appendages have mutuallyopposite slopes, the slope of each bow tip being contrary to the slopeof the respective stern for each appendage, said contrary slopesdefining a slope variation; wherein each appendage has at least one stepextending between the stern and the bow which defines said bow tips,said at least one step being symmetrically angled with respect to amedian symmetry plane of the hull and having notches associatedtherewith, the notches being wedged into said appendages; whereby saidappendages provide an induced hydrodynamic stability to the catamaran.2. A catamaran according to claim 1, characterized by the fact that saidsteps (6,7) form an inverted "V", proceeding from stern to bow.
 3. Acatamaran according to claim 1, characterized by the fact that saidsteps (10,11) form a "V" when proceeding from stern to bow.
 4. Acatamaran according to claim 1, characterized by the fact that saidsteps (15-20. 26-31) form at least two "V's", when proceeding from sternto bow.
 5. A catamaran according to claim 4, characterized by the factthat one of said steps (28, 31) which is the nearest to the stern isformed with a degrading tier of steps (35,40) sloping down from an outeredge of the bottom towards a longitudinal axis thereof.
 6. A catamaranaccording to claim 3, wherein each appendage has an edge on an outeredge thereof, said edge being bevelled further toward the inner edge. 7.A catamaran according to claim 1, wherein each appendage has an edge onan outer edge thereof, said edge being bevelled further toward the inneredge.